Common Infections of the Ear

EAR INFECTIONS COMMON INFECTIONS OF THE EAR

Ear infections, both of the inner and outer ear, are common in general practice.

OTITIS EXTERNA

Infection of the external auditory canal (EAC) is common and in certain circumstances can be life threatening. The EAC has high- ly effective mechanisms to prevent infection, which include migration of the skin covering the tympanic membrane and deep external canal, and the production of wax that has antibacterial and antifungal properties. Infection (otitis externa) will usually arise when these defences are overcome. Symptoms of otitis externa include otalgia, pruritus, discharge and hearing loss. The patient may experience pain with tragal pressure, or when the auricle is pulled upwards. The skin lining the ear canal is usually swollen and inflamed, and may be lined with debris. An approach to B SINGH KAREN COHEN diagnosis and management of otitis externa is shown in Table I. MB ChB, MMed (Otol) MB ChB, MCFP (SA), Dip Chief Specialist/ Obst (SA) Patients with non-infective otitis externa present with itch of the ear canal and they are usually in the 40 - 50-year age Professor and Head Honorary Lecturer group. On examination the ear canal is absolutely normal and Department of Division of Pharmacology there is absence of wax. The treatment of choice is application University of Cape Town Otorhinolaryngology, of combination steroid/antifungal/antibiotic ointment (e.g. Head and Neck Surgery Clinical Co-ordinator Kenacomb) with a cotton bud daily for 3 days. Nelson R Mandela School Antiretroviral Programme of Medicine Directorate: HIV/AIDS and Patients with fungal otitis externa present with ‘blockage’ of the ear. On examination white debris similar to the cream of University of Natal TB milk with black or white fungal spores is noted in the external Durban Provincial Administration ear canal. Treatment is to remove the debris by either syringing of the Western Cape or suction and then packing the ear canal with 10 mm wide and Bharath Singh received the 75 mm long ribbon gauze impregnated with combination MB ChB and MMed Karen Cohen completed steroid/antifungal/ degrees from the her medical training at the antibiotic ointment (e.g Kenacomb) for 48 hours. The treatment is repeated until the patient is asymptomatic. Fungal and bacteri- University of Natal in 1981 University of Cape Town, al infections commonly occur together. and 1988, respectively. His and trained and worked as a family physician at the areas of special interest The patients with bacterial otitis externa are usually young are head and neck surgery. Community Health Centre adults who present with severe otalgia and fever after swimming in Gugulethu, where she in infected waters such as dams, rivers or the sea. On examina- started an HIV clinic in tion there is marked oedema of the ear canal with complete 1998. She has recently occlusion of the lumen. The treatment includes packing the ear canal with 10 mm wide and 75 mm long ribbon gauze impreg- completed a registrar pro- nated with ichthammol glycerin, antibiotics and analgesics. The gramme in Clinical ear pack must be changed every 24 hours until the oedema sub- Pharmacology at the sides completely. University of Cape Town. Necrotising otitis externa with skull base osteitis This is a condition peculiar to elderly diabetic patients living in hot humid regions. The disease commences as osteitis of the

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Table I. Approach to otitis externa

Type Associated Characteristic features Precipitating Treatment symptom in external ear canal factors

Non-infective Itch Normal Nil Acetic acid drops/steroid drops if severe Fungal Hearing loss White debris with fungal Nil Acetic acid drops/combination spores steroid/anti-fungal/antibiotic (e.g. Kenacomb) ear pack if severe Bacterial Severe pain Oedema with occlusion Swimming Ichthammol glycerin, combination of the EAC steroid/antifungal/antibiotic (e.g. Kenacomb), intravenous co-amoxiclav if severe Necrotising Deep-seated Granulation tissue at Diabetes Intravenous antibiotics (see text) earache junction of bony and cartilaginous EAC

tympanic plate of the temporal bone presents with IX, X, XI and XII cra- ACUTE OTITIS MEDIA and then spreads posteriorly to involve nial nerve palsies. Acute otitis media is inflammation of the tympanomastoid bone and medial- • Stage 4 — Intracranial extension. the mucoperiosteal lining of the middle ly along the base of the petrous bone ear cleft, i.e. the Eustachian tube, tym- towards the foramen magnum. Diagnosis panic cavity, attic, mastoid antrum, The diagnosis is clinical and the gold- and mastoid air cells. When inflamma- The exact aetiology is unknown but en rule applies: Any diabetic patient tion affects the bony wall or spreads Pseudomonas aeruginosa has been who presents with deep-seated agonis- beyond the walls into the adjacent persistently isolated from pus swab. ing earache has skull base osteitis area, it is referred to as a complica- Pseudomonas has the propensity to until proven otherwise. The investiga- tion of otitis media, e.g. otitis media attach itself to diseased blood vessels tion of choice is technetium99 bone with meningitis or otitis media with leading to thrombosis, which explains scan. facial palsy. the necrosis of soft tissue and bone in diabetic patients who already have Treatment Otitis media is common in children, microangiopathy. The treatment of choice is intravenous with peak incidence in the 1 - 2-year antibiotics consisting of aminoglyco- age group, and usually follows upper Four stages of the disease are recog- side, piperacillin and metronidazole respiratory tract infection. The infec- nised: for a minimum period of 6 weeks. In tion spreads to the middle ear via the • Stage 1 — Osteitis of the tympanic those patients with impaired renal Eustachian tube. plate of temporal bone only. The function, the recommended treatment patient presents with deep-seated, is intravenous ciprofloxacin and Four stages of acute otitis media are agonising and unrelenting earache metronidazole. recognised: which is worst at night. The sign •Stage 1 — Stage of tubal occlusion that heralds osteitis of the tympanic Response to treatment is monitored by is characterised by negative middle plate is granulation tissue on the performing serial technetium bone ear pressure with an effusion. Adult floor of the ear canal at the junc- scans at 3-weekly intervals. patients complain of a blocked ear tion of the tympanic plate and the Antibiotics are only stopped when the and autophonia (echoing of one’s cartilaginous portion of the ear bone scan is negative. own voice). The ear drum is retract- canal. Prognosis ed and the light reflex may be • Stage 2 — Osteitis of tympanic absent. There may be clinical evi- plate and stylomastoid bone. The Prognosis is dependent on the stage of dence of middle ear effusion, for patient presents with lower motor the disease. With stage 1 disease the example air bubbles and fluid in neuron VII cranial nerve palsy. prognosis is excellent; complete recov- the middle ear space.1 • Stage 3 — Osteitis of the base of ery occurs in all patients. The progno- • Stage 2 — Stage of presuppura- the petrous bone with involvement sis is poor in advanced disease. tion. The middle ear effusion of the jugular foramen and becomes infected and increases in hypoglossal canal. The patient

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quantity and the patients have a Otitis media caused by pneumococcus By 24 hours, two-thirds of children fever and complain of throbbing is least likely to resolve spontaneously, had recovered spontaneously, whether earache. Children often vomit. The and it is important that first-line empir- or not they were treated with antibi- tympanic membrane is inflamed ic antibiotics treat pneumococcal infec- otics. Overall, antibiotics showed only and bulges outwards.1 tion adequately. There has been a modest benefit over placebo in pain • Stage 3 — Stage of suppuration. worldwide increase in drug-resistant reduction. Seven per cent fewer chil- The intratympanic pressure increas- Streptococcus pneumoniae (DRSP), dren had pain after 2 - 7 days, which es and occludes the blood supply and empiric therapy needs to take this means that 15 children needed to be resulting in necrosis and rupture of into account. Of importance, resist- treated with antibiotics to prevent 1 the tympanic membrane. This event ance is due to a change in the affinity child from experiencing pain after is characterised by the patients of penicillin-binding proteins in the 2 - 7 days.2 reporting excruciating pain fol- bacterial cell wall and not to beta-lac- lowed by a ‘pop’ and discharge, tamase production, as is the case with Because many cases of otitis media with immediate relief of earache. resistant H. influenzae. Thus DRSP will resolve spontaneously, benefits of On examination a central perfora- has increased resistance to all beta- antibiotic therapy must be weighed up tion of the tympanic membrane is lactam antibiotics, including the against the risk of adverse reactions to noted with pus oozing from the cephalosporins.2 antibiotic therapy. In an older child middle ear into the external ear who is otherwise well, a delay in initi- canal.1 Table III gives the minimum inhibitory ating antibiotics may be considered. • Stage 4 — Stage of resolution. In concentration required to treat DRSP Antibiotics may, however, play an 80% of patients complete resolution for a selection of beta-lactam antibi- important role in reducing the risk of occurs: the otorrhoea subsides and otics that are commonly prescribed for complications of otitis media, particu- the perforation heals spontaneously the treatment of respiratory tract infec- larly mastoiditis. after a week. In 20% of patients, tions. The table includes the antibiotic incomplete resolution occurs: the level that is reached at the site of Recommended first-line perforation and otorrhoea persist action — the middle ear fluid. Of treatment for otitis media or the perforation heals with middle importance, cefpodoxime, cefaclor An assessment of the risk of infection ear effusion.1 and loracarbef are ineffective agents with DRSP must be made. Risk factors for treatment of DRSP. Amoxicillin for infection due to resistant Acute otitis media is the most common remains the drug of choice when treat- Streptococcus pneumoniae are as fol- reason for antibiotic prescription in ing otitis media due to DRSP, and lev- lows: children. Accurate identification of els adequate for the treatment of DRSP • age less than 2 years the causative pathogen can only be may be attained by using higher • antibiotic treatment in the last 1 - 3 made by performing tympanocentesis doses. Ceftriaxone is an excellent months — an invasive procedure that is agent, but must be given parenterally, • attendance at a day care centre. almost never performed by clinicians. and is therefore most useful in treating Therapy is therefore empiric, based on the younger child with otitis media A child who is at high risk of DRSP clinical studies identifying causative who is very unwell and cannot tolerate infection should be treated empirically organisms, and on knowledge of oral medication.2 with high-dose amoxicillin (80 - 90 antibiotic susceptibility patterns of the mg/kg/day of amoxicillin, in 3 divid- most common causative organisms. Benefits of antibiotic ed doses). Those with a low risk of treatment for otitis media infection with DRSP may be treated Predominant pathogens are A Cochrane review of antibiotics for with amoxicillin 40 - 45 mg/kg/day. Streptococcus pneumoniae, acute otitis media in children showed Haemophilus influenzae and no reduction in pain at 24 hours in Management of clinically Moraxella catarrhalis (see Table II). children treated with antibiotics, com- defined treatment failure pared with those treated with placebo. Treatment failure is a lack of clinical improvement after 3 days of therapy, with persistence of ear pain, fever, Table II. Otitis media — causative organisms and redness and bulging of the tympanic membrane, or ottorrhoea. Organism Percentage Treatment may fail due to lack of com- pliance, due to infection with DRSP S. pneumoniae 40% which has been inadequately treated, H. influenzae 20% or due to inappropriate choice of M. catarrhalis 10% antibiotic (see Table III), or too low a Other streptococci 5 - 10% dose of amoxicillin. Treatment with Staphylococci 5% amoxicillin may also fail in cases No organism isolated 10 - 20% where the causative organism is resist-

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Table III. Activity of a selection of beta-lactam drugs, at standard doses, against DRSP2

Beta-lactam MIC90 (µg/ml) MIC90 (µg/ml) MIC90 (µg/ml) Peak serum Peak middle ear antibiotic Penicillin- Penicillin- Penicillin- concentration fluid concentration susceptible intermediate resistant (µg/ml) (µg/ml) strain strain strain

Amoxicillin 0.03 0.1 - 1 2 - 4 3.5 - 7 1 - 6 Ceftriaxone 0.06 1 1 - 4 171 35 (e.g. Rocephin) Cefuroxime 0.125 1 - 4 4 2 - 7 1 (e.g. Zinnat) Cefpodoxime 0.06 1 - 4 4 1 - 4 0.2 (e.g. Orelox) Cefaclor 1 64 128 7 - 13 0.5 - 4 (e.g. Ceclor) Loracarbef 2 64 128 13 - 19 2 (e.g. Lorabid)

Table IV. Complications of otitis media

Extracranial complications Presentation

Post-auricular abscess Post-auricular swelling Facial palsy Drooling of saliva from angle of mouth and inability to close the ipsilateral eye on the same side Labyrinthitis Dizziness with nausea and vomiting Bezold’s abscess Swelling of the mastoid tip Petrous apicitis Ipsilateral otorrhoea, VI cranial nerve palsy, and facial pain

Intracranial complications

Extradural empyema ‘Silent’ or nuchal rigidity and pyrexia Subdural empyema Headache, pyrexia, with or without hemiparesis Brain abscess: • Temporal lobe Nuchal rigidity, aphasia, hemiparesis • Cerebellar Dizziness and unstable gait • Lateral sinus thrombosis Headache, pyrexia, and rigors, pain over the anterior border of sternocleidomastoid muscle Meningitis Severe headache, pyrexia, neck stiffness Otitic hydrocephalus Headache, nausea, and vomiting

ant due to beta-lactamase production CHRONIC OTITIS MEDIA appropriate treatment can be instituted (e.g. beta-lactamase-producing H. immediately. Chronic otitis media is osteitis of the influenzae).2 mastoid bone and is characterised by Cholesteatoma persistent otorrhoea and tympanic Suitable antibiotics for management of Cholesteatoma is accumulated desqua- membrane perforation. Two types are treatment failure include high-dose mated squamous epithelium in the mid- recognised — non-cholesteatomatous amoxicillin-clavulanate (80 - 90 mg/ dle ear cleft. Under normal circum- and cholesteatomatous chronic otitis kg/day of the amoxicillin component, stances squamous epithelium is present media. The former is usually associat- with 6.4 mg/kg/day of clavulanate) only in the outer layer of the tympanic ed with central perforation and the lat- or intramuscular ceftriaxone 50 mg/ membrane and the skin of the external ter with posterior superior marginal kg/day for 3 days. ear canal. No squamous epithelium is perforation. It is important to make the present in the middle ear cleft. distinction at the initial visit, so that The underlying pathophysiology in

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Infection of the external temporal bone, resulting in complica- • Step 3. Intravenous antibiotic thera- auditory canal (EAC) is tions associated with chronic otitis py. A pus swab is taken and ampi- common and in certain cir- media. cillin (50 mg/kg/d) with metronidazole (20 mg/kg/d) are adminis- cumstances can be life- The diagnosis of cholesteatoma is clin- tered intravenously for 48 hours. threatening. ical, the presence of whitish, cheese- The response is reviewed. If the like material is diagnostic. The most otorrhoea is subsiding, then contin- common site is the attic and a polyp ue with the treatment another 8 Patients with bacterial otitis in the ear canal often heralds the pres- days. If the otorrhoea remains externa are usually young ence of cholesteatoma. unchanged check the culture and adults who present with sensitivity results of the pus swab severe otalgia and fever The treatment of choice for and prescribe appropriate antibi- after swimming in infected cholesteatoma is complete surgical otics and continue treatment for 10 waters such as dams, rivers excision of the cholesteatomatous sac days. Patients in whom otorrhoea by a modified radical mastoidectomy. fails to subside are moved to the or the sea. There is no place for conservative next step. treatment. The success rate of drying the ear Any diabetic patient who with conservative treatment (steps Management of a non- 1, 2, and 3) is 90%. presents with deep-seated cholesteatomatous • Step 4. Mastoidectomy is the sur- agonising earache has discharging ear gical procedure for eradicating dis- skull base osteitis until The treatment aim is to dry the ear so ease from the mastoid bone. It proven otherwise. that spontaneous healing of the tym- involves exenterating all the dis- panic membrane can take place. eased mastoid bone with a micro- There are four sequential steps to surgical drill and removing infected Because many cases of oti- achieve a dry ear: granulation tissue from the middle tis media will resolve spon- • Step 1. Antibiotics, aural toilet, and ear, attic and mastoid cavities. taneously, benefits of application of eardrops. The 10- Simple or cortical mastoidectomy is day antibiotic treatment consists of antibiotic therapy must be recommended for the non-choles- amoxicillin, co-amoxiclav or teatomatous ear. weighed up against the cefuroxime. Aural toilet must be risk of adverse reactions to performed twice daily with cotton Mastoidectomy is a surgical proce- antibiotic therapy. wool and sticks (commercially man- dure to eradicate disease from the ufactured cotton wool buds are not middle ear cleft and basically two recommended). Immediately after types are recognised — cortical and cholesteatoma formation is Eustachian dry mopping, ear drops containing modified radical mastoidectomy. tube dysfunction. 0.5% phenol must be applied. This Cortical mastoidectomy is indicated With occlusion of the Eustachian tube treatment must be continued for 1 for non-cholesteatomatous chronic oti- a negative pressure is created within month. Patients in whom this treat- tis media and modified radical mas- the middle ear cleft, resulting in medi- ment fails are moved to the next toidectomy for cholesteatomatous al retraction of the superior posterior step. chronic otitis media. part of the tympanic membrane (pars • Step 2. Remove possible predispos- flaccida) into the epitympanum (attic). ing factors. Tonsillectomy, ade- The anatomical difference between the The squamous epithelium in the retrac- noidectomy and bilateral antral two is that in the modified radical tion pocket continuously desquamates wash-out must be performed. mastoidectomy the bony partition and if successful outward migration Radiograph of the paranasal sinus- between the external ear canal and does not occur, the squamous epitheli- es and lateral neck may be request- the mastoid cavity is excised complete- um accumulates in the pocket and this ed to confirm or exclude sinusitis ly while in the cortical mastoidectomy is referred to as cholesteatoma. As and/or enlarged adenoid glands. it is retained. The functional difference more desquamated squamous epitheli- Remember that radiological between the two procedures is that the um accumulates, the retraction pocket absence of adenoid gland hyper- modified radical mastoidectomy is gets larger and extends into the mas- trophy does not exclude chronic associated with approximately 60 toid antrum. Cholesteatoma is consid- adenoiditis. After removal of pre- decibel hearing loss. ered a serious condition because it disposing factors, continue with promotes the growth of bacteria and aural toilet and application of Mastoidectomy can be performed at releases proteolytic enzymes, which eardrops for 1 month. If otorrhoea any age depending on the indication. cause bone resorption. Both these fac- fails to subside, then move to the Tympanoplasty is a surgical proce- tors are responsible for the spread of next step. dure to restore hearing and it ranges the infection within and outside the

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IN A NUTSHELL from a simple myringoplasty (recon- Intracranial complications must be sus- struction of the tympanic membrane) to pected in all patients who present with The tragus, the tortuous S-shape more complex ossiculoplasty (recon- severe headaches, nuchal rigidity or course of the ear canal and the obliq- struction of the ossicles). localising neurological signs with uity of the tympanic membrane offer chronic discharging ears. The investi- protection to the delicate middle ear Unlike mastoidectomy, tympanoplasty gation of choice is computed tomogra- structures. cannot be performed at any age. It phy scan of the brain. The treatment The underlying pathophysiology of must be performed at an age when for all patients with otogenic intracra- otitis externa is maceration of the skin the conditions are optimal to give the nial complications is intravenous of the external ear canal. The hair best results. The recommended age for antibiotics (ampicillin 60 mg/kg/d, and lipid content of cerumen renders tympanoplasty is 10 years and older metronidazole 20 mg/kg/d, and chlo- the ear canal impervious to water, because after this age not only does ramphenicol 30 mg/kg/d), mastoidec- thus preventing infection. the incidence of upper respiratory tomy and surgical drainage of the tract infection decrease but, more intracranial abscess. The neurosurgical Wax is protective and should not be importantly, the Eustachian tube func- procedure and mastoidectomy must be removed. It contains lysozyme and tion improves. performed under the same anaesthesia immunoglobulins that inhibit the with the neurosurgical procedure growth of bacteria and fungi. Complications are commonly associat- always preceding the mastoidectomy. Four types of otitis externa are recog- ed with chronic rather than acute otitis Surgery must be undertaken as soon nised, non-infective, fungal, bacterial media (see Table IV). They can be as possible, not later than 12 hours and diabetic. divided into extracranial and intracra- after presentation.3 nial complications. Diabetic otitis externa is a life-threat- Otogenic intracranial complication is ening condition and in order to pre- The most common extracranial compli- a serious condition with a mortality of vent mortality early diagnosis and cation is post-auricular subperiosteal 10 - 30%. treatment with intravenous triple abscess (mastoiditis). Facial palsy is a antibiotics is mandatory. rare complication of chronic suppura- Tuberculous otitis media is a dis- The causative organisms in acute oti- tive otitis media; if present then TB ease of children — 80% are younger tis media are Haemophilus influenzae mastoiditis must be suspected. The than 10 years of age. The typical clini- and streptococcus and the treatment treatment for all extracranial complica- cal features include painless and pro- of choice for children living in rural tions is urgent intravenous antibiotic fuse otorrhoea, multiple tympanic areas is procaine penicillin and therapy, consisting of ampicillin membrane perforations, pale granula- amoxicillin and for those living in 60 mg/kg/d, metronidazole tions, lower motor neuron facial palsy urban areas either Augmentin or 20 mg/kg/d and mastoidectomy per- (40% incidence), disproportionate cefuroxime. formed as soon as possible, preferably hearing loss, and bone necrosis with within 12 hours of presentation. sequestra formation. Evidence of TB in Two types of chronic otitis media are other sites reinforces the diagnosis, recognised — cholesteatomatous and e.g. pulmonary TB (95%) and pre- non-cholesteatomatous chronic otitis auricular lymphadenopathy (23%). media. The diagnosis is confirmed on histol- Cholesteatomatous chronic otitis ogy of granulation tissue biopsied media is regarded a serious condition either from the middle ear space or because cholesteatoma releases pro- 4 mastoid cavity. The treatment is antitu- teolytic enzymes that cause bone berculous therapy for a minimum peri- resorption with extension of infection od of 6 months. into the bony labyrinth, facial canal and intracranially. References available on request. Chronic otitis is regarded as a life- threatening condition because of its association with intracranial complications, which carries a mortality of 10 - 30%.

Tuberculous otitis media is common in children. The golden rule is that any child who presents with ipisilateral otorrhoea and lower motor neuron VII cranial nerve palsy has tuberculous otitis media until proven otherwise.

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